I use the two finger method also as it is more convenient and doesn't require you to master another device like the pendulum (which is prob not anymore accurate). You have to make sure you're properly hydrated and not switched. Even then, I think it is not foolproof as sometimes things seem to be blocked. Simple EDS devices are not terribly expensive, but you do have to have samples to test. You also have to master useing the stylus and finding points which is not all that easy. I looked at the SCIO, but was not able to get my arms around how it works before they took it off the market. I am looking at the ETA scan now which seems to be a similar machine, but have not found a lot of info on it.